I would give the Remix 69 and the Pyranha Burn (large) a try, both boats have the qualities you are interested in. I think the Remix may be a good fit for you since you are used to longer boats. The whole idea behind the Remix was to reintroduce length and speed to the boat market, both have been on a steady decline since the 90's. Then again speed is all relative, and the newer boats are able to do more with less, and the shorter length and increased rocker make modern boats far more maneuverable than anything that was out in the 80's.
The Burn is a great design too (I paddle for Pyranha, but that's my honest opinion). The Burn has a flatter hull and more defined edges than the Remix, which make the boat really snappy in and out of eddys. The edges and flat hull also make the Burn a respectable surfer for a creek/river running boat. As for big water, I think the Burn does very well in this realm, because the hull allows you to 'surf' your way around the river. Displacement-style hulls tend to stick in the water more, which can make them less manueverable in big water. If the edges on the Burn feel too agressive for you, then you might check out the Pyranha Everest, which is coming out soon. It's basically a bigger, longer Burn with softer edges.
Rachet backbands are now pretty standard in kayak outfitting, and I have not had any problems (in the seven or so years that rachets have been used) with my backbands giving way, even after big pitons. If the rachets still make you nervous, you can always carry an extra set along with some zip ties in case one or both of the rachets fail on you in the middle of a run.
Best of luck with the boat hunting and enjoy your return to the sport. This is a good time to get back into it, there a lot of great boats out there. The new designs have really made down river paddling a lot more enjoyable.